About Mexico's Reservoirs

Located along the upper Santiago River, this basin covers a mix of lake and reservoir systems draining toward the Río Grande de Santiago, surrounded by agricultural land. It follows a pronounced seasonal cycle, with reservoirs typically drying during the early part of the year before refilling as the wet season begins. Vegetation across the basin ranges from fresh growth to fully dried patches resembling exposed soil, with water hyacinth present in some water bodies and cyanobacteria detected at more than half of the monitored sites.

Located in the upper reaches of the Lerma River system in the State of México, this basin sits on the Mexican Plateau at higher elevation, characterized by urbanized terrain interspersed with reservoirs feeding the headwaters of the Lerma River. The basin experiences a defined wet season with flooding common in late summer, and reservoirs tend to stagnate with limited water movement during drier months. Across the monitored water bodies, cyanobacterial blooms and floating or emergent vegetation are common, with several sites showing consistently stagnant conditions and visible seasonal drying.

Situated downstream of Lerma 1, spanning a broader stretch of the Lerma River through the surrounding agricultural plains, this basin covers flatter farmland interspersed with mid-sized reservoirs. Seasonal drying is the dominant pattern across the basin, with most water bodies visibly shrinking during drier periods. Vegetation cover varies widely across sites, ranging from high emergent growth and dense macrophyte cover to sparse patches and mixed land with scattered vegetation, with water hyacinth also observed in isolated pockets.